What is a firewall?

You’ve probably heard the word “firewall” a few times in recent years. There was even a 2006 Hollywood movie of the same name starring Harrison Ford, Paul Bettany and Virginia Madsen.

But what is a firewall, and why do they matter?

Keeping the bad guys out

At the most basic level, a firewall is a system that prevents unauthorised access to a network. The firewall acts like a bouncer at the entrance to the network, checking the identification of everyone who tries to enter. Any unauthorised access attempt is blocked automatically.

How does a firewall work?

Before you can properly understand why firewalls matter, you first need to understand a tiny bit about how data is sent between computers.

Say you email a document to a colleague. Your computer splits the document into tiny pieces called packets which are then sent one at a time to your colleagues computer. Each packet contains additional information that tells the recipient’s computer how to rebuild the document from the packets – and where the packets are coming from. This whole process can be completed in a matter of seconds.

Network data transfers aren’t fool proof though. Packets can get corrupted or lost during transfer. Or they can be intercepted and modified by hackers.

A firewall adds an important layer of protection into the data transfer mechanism. The firewall sits between your computer and the recipient’s, checking every packet that passes through. Any network traffic that has been faked, is coming from an unauthorised or unrecognised source, or is otherwise suspicious is blocked automatically.

The firewall does a lot more besides too. It monitors all network traffic, preventing hackers from breaking into your computer or other internet-connected devices.

Why do firewalls matter?

In a business environment, the firewall is installed at the edge of the network; all network traffic has to pass through the firewall, and is analysed in transit. And the same is true of application firewalls like those included with Panda Dome that are installed on home computers.

Effective network security works on the principle of blocking suspicious traffic before it reaches your computer. In a corporate network, that means stopping hackers before they can access the network. At home, you need to drop/block bad network traffic before it can reach the data stored on your computer.

A firewall is not the same as antivirus – it does not check to see whether incoming packets contain malware. But it does automatically block the most suspicious network traffic to keep criminals out. Like antimalware systems however, a good firewall is also regularly updated so that it is capable of blocking the latest threats and suspicious activities.

And this automated checking is an important tool for raising the overall level of protection for your home computer and data.

To learn more about firewalls, please take a look at the Panda knowledgebase. And if you’d like to protect your computer with a firewall now, please download a free trial of Panda Dome Security.